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[PATCH] ppc32: Simplified load string emulation error checking 

The error checking for emulation of load string instructions was overly
generous and would cause certain valid forms of the instructions to be
treated as illegal.  We drop the range checking since the architecture
allows this to be boundedly undefined.  Tests on CPUs that support these
instructions appear not do cause illegal instruction traps on range errors
and just allow the execution to occur.

Thanks to Kim Phillips for debugging this and figuring out what real HW was
doing.

Signed-off-by: Kumar Gala <kumar.gala@freescale.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Kumar Gala 2005-05-28 15:52:13 -07:00 committed by Linus Torvalds
parent 91f9855a7a
commit 92b4dc1625
1 changed files with 1 additions and 6 deletions
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7
arch/ppc/kernel/traps.c
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@ -408,12 +408,7 @@ static int emulate_string_inst(struct pt_regs *regs, u32 instword)
/* Early out if we are an invalid form of lswx */
if ((instword & INST_STRING_MASK) == INST_LSWX)
if ((rA >= rT) || (NB_RB >= rT) || (rT == rA) || (rT == NB_RB))
return -EINVAL;
/* Early out if we are an invalid form of lswi */
if ((instword & INST_STRING_MASK) == INST_LSWI)
if ((rA >= rT) || (rT == rA))
if ((rT == rA) || (rT == NB_RB))
return -EINVAL;
EA = (rA == 0) ? 0 : regs->gpr[rA];